Resistance to biodeterioration of thermally modified Eucalyptus grandis and Tectona grandis short-rotation wood

Abstract

ABSTRACT This study aimed to assess the biological resistance of thermally modified Eucalyptus grandis (eucalypt) and Tectona grandis (teak) short-rotation wood. Different treatment categories were investigated: untreated and thermally modified eucalypt and teak wood. The thermal modification was carried out at 160 °C in a closed system (pressurized) hygrothermal process. The wood was tested for resistance against brown-rot (Postia placenta) and white-rot (Trametes versicolor) fungi for 12 weeks, according to the soil-block method. The wood was also tested for the attack of subterranean (Nasutitermes corniger) and dry-wood (Cryptotermes brevis) termites, respectively for 28 and 45 days. In both cases, non-choice feeding tests were used. The thermal modification did not improve the resistance of eucalypt and teak short-rotation wood against the deterioration caused by both brown-rot and white-rot fungi. On the other hand, the process improved the resistance of both species against the attack of the subterranean termites, and specifically for eucalypt, against dry-wood termites. The resistance of teak was higher than that of eucalypt for both conditions (untreated and thermally modified) and xylophagous insects tested.